Method of charging secondary batteries.



APPLICATION FILED DEC. 3. i913- Patented May 22, 1917.

wi/h maow UNITED STATES PATENT OFFICE EDWARD B. JACOBSON, OF PITTSFIELD,MASSACHUSETTS, ASSIGNOR T HENDEE MAN U- EACTUBING COMPANY, OFSPRINGFIELD, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

METHOD OF CHARGING SECONDARY BATTERIES.

Specification of Letters Patent.

Patented May 22, 1917.

Application filed December 3, 1913. Serial No. 804,530.

To all whom it may concern:

I Be it known that I, EDWARD B. .JACOBSON, a citizen of the UnitedStates, resldmg at Pittsfield, in the county of Berkshire, StateCharging Secondary Batteries, of which the following is a description,reference being bad to the accompanying drawing and to the figures ofreference marked thereon.

My invention relates to the-method of charging secondary batteries andhas for its principal object the charging of batteries in such mannerthat their operation and the operation of the apparatus connected withthem are substantially fool proof.

It is a well known fact that the proper charging and care of storagebatteries has heretofore required very skilful attention. Wherebatteries have been used in large units as for instance upon electricvehicles of the various types, and charging stations of considerablesize have been provided, it has been possible for electricians andowners of cars to give this attention. In the usual case more than oneset of batteries is provided, and one is used while the other isbeingcharged. In the case of small batteries for lighting and startingof machines run by hydrocarbon engines however, the batteries are verymuch smaller, sosmall that the skilful care and automatic appa ratusused in their charging becomes too great an expense to be maintained bythe individual owner. It is to meet the demand for a satisfactory foolproof method of charging these small units, and particularly to meet thedemand for such a method for use upon motor cycles and vehicles of liketype that my invention has been made.

On vehicles of the character of motor cycles, the available space forapparatus is very limited and furthermore the vehicle is used underconditions much more extreme than are the average vehicles of the fourwheel type. Still further these vehicles cost so little and are so lightin weight as not to warrant the provision of extra batteries andcomplicated apparatus. As will be seen, my improved method of chargingnot only enables a single battery to be continuously used, but alsoenables it to be charged and maintained charged by the most carelesswithout damage and with a minimum weight of appurtenant apparatus.

My improved method of charging batteries consists in applying to thesecondary battery from the charging generator or other suitable sourcefor an indeterminate period and virtually continually, and irrespectiveof the condition of the battery, a charging current of a value too smallto result in harmful effect uponthe battery when the application iscontinued after the battery has become fully charged. Prefstantiallyuniform maximum value and are separated by an appreciable time interval,whereby the heat generated by the passage of such current through thebattery after the battery has become fully charged is insufficient totax the capacity of radiation of the battery or to raise its temperaturesubstantially above its normal operating temperature. Y

My invention may be best understood from a preliminary description ofthe apparatus by which the same is carried into use, and accordingly Ihave illustrated such apparatus on the accompanying sheet of draw ings.

Referring to the drawings, G is a generator of the direct current types,capable of use as a motor in the well-known manner. B is a secondarybattery to be charged. The negative pole of the generator is connectednormally to the negative pole of thebattery through the groundconnection indicated or through any suitable conductor. From thepositive pole of the generator to the positive pole of the batteryextends a conductor C which as shown is normally open at contacts 2, 3.These contacts are a part of a regulator R.

The regulator R comprises a coil 0 in series with the conductor C andwound upon a core {L The core 4 is made in two sections separated bysuitable non-magnetic material 5. On the opposite end of the core 4 fromthe coil 0 is a second coil 0' also in series with conductor 0, andwound in the same direction upon the core as coil 0, and in addition apotential coil 79 connected across the terminals of the generator G.Coil 0 normally acts in the same direction as coil p. The contacts 2, 3referred to are mounted at .erably this current is of a pulsatingcharacter, the pulses of which have a subthis end of the core. Attheopposite end of the core are mounted normally closed contacts 6, 7 inthe shunt field F of the generator. Both the contacts 2 and 6 aremovable contacts and are carried on suitable armatures 8, 9. Armature 9may be polarized. When the coils of the regulator R are denergized, thecontacts 2 and 6 are retracted by their resiliency or by the res1l1-ency of connected springs.

The generator G is also provided with a series field winding S connectedbetween the positive pole of the generator and the positive pole of thebattery by means of a conductor D.

The method of my invention is carried out by this apparatus as follows:The generator G is driven from the hydrocarbon motor of the vehicle byany suitable connection, with or without intermediate gearing, and whenso driven, charges the storage battery B over the conductor C. When thehydrocarbon motor is at rest however it may be started by usin thegenerator as a motor, the generator a being supplied with power over theconductor D and turning the en 'ne over sufiiciently to start it. 'Inthe rst case when the batteries are being charged, the shunt field F isused, whereas when the engine isibeing started, vthe generator beingused as a motor, the series fieldS is used.

. maximum value of the ch The engine having been started and thegenerator G operating as such, as soon as the voltage of the generatorrises to such a value that the potential coil 1) draws its armature 8and contact 2 up, the circuit C between the generator and batteries QBis closed at contacts 2, 3, and charging current flows to the battery,the potential at which the coil [2 acts being above that of the batterysufficiently to prevent reverse current. The arging current isdetermined by the series coil 0 which attracts its armature and contact6 as soon as the current reaches a determinate maximum value. This opensthe shunt field circuit at contacts 6 and 7 (the resistance R is bridgedacross the contacts to prevent sparking) and immediately the voltage ofthe generator begins to fall, and with it' the current in the. conductor0, until the current becomes too weak to hold the contacts 6, 7 separatewhereupon these contacts again close, and the generator voltage risesquickly to its former value, the shunt field building up as the voltagerises, whereupon the current having again reached the determinate valueat which contact 6 is operated, the field F is again broken, and so on.

Therejs thus a pulsating. or intermittent charging current supplied thebattery over the conductor C. The proportions of the series coil 9 aremade such thatthe value of this charging current, and the total quantityof current applied to the battery durthe battery.

ing any given period of time are too small to effect harm to the batteryin case continued after the battery has become fully charged. In otherwords, the total quantity of charging current applied in any given timeis too small to tax the capacity of radiation of the battery, and tosubstantially increase its operating temperature above normal. Thereforeno matter how long the charging current is appliedto the battery,excessive gasing at the negative electrodes or excessive heat whichwould bring about buckling of the plates of the battery, cannot takeplace. This effect is augmented greatly by that feature of my method ofcharging which consists in the application of a pulsating current, thepulses of which are separated by time intervals of appreciable length.Thus the maximum current may be made quite high, but owing to the timeinterval between pulses, the battery recovers itself before itstemperature rises substantially above its normal operating temperature.This maximum value is maintained substantially uniform irrespective ofthe condition of the battery, since the coil 0 of the regulator is acurrent coil.

Obviously in the practice of my method as aforesaid, the battery B maybe retained continuously in connection with the generator without anyattention whatsoever on the part of the operator of the vehicle inconnection with which it is used. When discharged for any purpose,whether greatly as. in starting the engine, or slightly as when used forlighting, its discharging commences immediately, and the application ofthe charging current is continued as long as the vehicle lsin operation.This length of time may be four or five times as long as is necessary toagain fully charge the battery, but the charging current is not removedfrom the battery at. any time except when the voltage of the generatoris too low to charge Irrespective of the extreme variations of speed ofthe generator which occur in the use of a motor-cycle, the regulator Rkeeps the maximum value of the current at thesame determinate value, theonly effect of spurts and other variations of speed being to slightlyincrease the number of current impulses produced through theoscillations of the contact 6; During this time the actual variation ofgenerator voltage is insufiicient to be detrimental to good opera tionof lights or other load on the battery.

There is no further apparatus needed than that illustrated to carry outthis method and yet with this small quantity of apparatus, the resultsare secured just as reliably as they are secured under the eye and handof an expert in a charging station equipped with complicated apparatus.

Through the simple provision of the generic spirit and I desire extraseries coil 0 in connection with the potential coil p, reverse currentin conductor G is effective to open conductor C at contacts 2, 3 andprevent discharge of the battery through the generator when thegenerator is idle. The generator is operated from the battery as a motorby a circuit closing switch in conductor D.-

I am aware that batteries have heretofore been charged by maintainingthe charging current at a substantially constant value during thecharging period, and I make no claim thereto. My invention goes fartherand fixes both the character and the value of the current fwith respectto the capacity of radiation of the battery being charged and its normaloperating temperature, and irrespective of its condition of charge.While I have disclosed the best form of my invention now known to me, Idesire to have it understood that the method of my invention may bevariously carried out without departing in any way from its to cover inthe annexed claims all such variations.

Having thus described my invention what I claim and desire to secure byLetters Patent is- 1. The method of charging and maintaining charged astorage .battery which consists in applying to said battery for anindeterminate time and irrespective of the condition of charge, acharging current of pulsating character, the maximum of which is of adeterminate substantially uniform value and unaffected by the conditionof charge of the battery, the total of said curthe condition of charge acharging current of a pulsating character, the maximum of which is of adeterminate substantially uniform value unaffected by the condition ofcharge of the battery, the total quantity of such current in any givenperiod being such that gasing at the negative electrodes is not producedwhen the current is continued after the battery has become fullycharged.

3. The method of charging secondary batteries and maintaining the samein charged condition, which consists in applying for an indeterminateperiod of time irrespective of the condition of charge of the batterycharging current of'a pulsating character, the pulses of which areseparated by an appreciable interval of time, and the total quantity ofwhich in any given period of time is insuflicient to produce harmfuleffect upon the battery when the current is continued after the batteryhas become fully charged.

In testimony whereof, I affix my signa ture, in the presence of twowitnesses.

EDWARD B. JACOBSON. Witnesses:

CHARLES L. STURTEVANT, JOHN D. STEPHENS.

